#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
  unsigned long long int n , m;
    cin >> n >> m ;
    
    unsigned long long int ans = n*m - 1;
    
    printf("%llu\n",ans);
    
    
    return 0;
}